Process for increasing tensile strength of cellulose and product



Patented Feb. 20, 193.4

PROCESS FOR INCREASING TENSILE STRENGTH OF CELLULOSE AND PROD- UCT August J. Pacini, Chicago, Ill., assignor to Milprint Products Corporation, Wis., a corporation of Wisconsin Milwaukee,

No Drawing. Application May 4, 1931 Serial No. 535,086

- 5 Claims.

. My invention relates to a process for improvement' in the properties, particularly the tensile strength, of cellulose materials, such as cotton, and to the product resulting from said process.

My invention consists in subjecting cellulose or textiles of cellulose materials to artificially produced ultra-violet. radiation under controlled conditions effective to render the fibres of cellulose of greater tensile strength thanthey possess without this treatment.

It is commonly accepted that cellulose or textiles of cellulose are-subject to deterioration, usually manifested as a loss in tensile strength, by the action of natural agents such as sunlight, and that the ultra-violet component of sunlight is charged with the greatest disintegrating effect (Johnson Textile Fabrics- -page 309; Journal Society of Dyers and Colourists, Vol. 33, 1917, page 17; and Der Textilterichte 1924, page 745) 2o Ultra-violet radiation is charged with the development or formation of oxycellulose which is a compound similar to that produced by overbleaching and which, by reason of its structureless, brittle or friable properties, is lacking in strength and lose.

In accordance with this invention, however, cellulose is not only not weakened, but materially increased in tensile strength by subjection to, or treatment by, ultra-violet radiation under controlled conditions. This increase in the tensile strength properties is accomplished by exposure of the fibres or fabric to intense ultra-violet radiation of proper quantity and quality for a period prior to the detectable formation of oxycellulose. If the treatment is prolonged until oxycellulose is detectable, the process of deterioration sets in and the cellulose fibres are weakened instead of being strengthened. With a 1'10-volt quartz mercury'vapor lamp, operating at maximum intensity, about"'70 volts, and suspended substantially six inches from the fibres or fabric, the period of exposure has been found to materially increase tensile strength through a range of from eighttenths of a second to four and one-half seconds. The period during which oxycellulose does not form, or at least is not detectable, may extend as long as fifteen or twenty minutes, depending upon such factors as the texture and number of fibres, the relative surface exposed and the intensity and quality of ultra-violet radiation, but as the length of time of exposure approaches thepoint of formation of detectable oxycellulose, the degree of increase in tensile strength becomes less. Therefore, during this period prior to the formahence reduces the tensile strength of the cellution of detectable oxycellulose, the maximum increase in tensile strength of the cellulose determines the point at which to stop the treatment. As an instance of the efiicacy of this method of increasing tensile strength of cellulose, cotton fibres which have been given treatment equivalent to that which they would receive as fabric in the usual laundering process, havebeenincreased in tensile strength as much at 21.21% when exposed for a period of eight-tenths of a second to the o5 ultra-violet radiation from a 110-volt quartz mercury arc lamp at six ,inches distance from the material.

During this period prior to the formation of oxycellulose detectable by thelznown methods i of detection, a change in the cellulose takes place which increases the tensile strength very materially. I do not rest my invention upon any theory as to what the character of the change is, but tests indicate that by virtue of the ultra- 7 violet radiation the alkali soluble component of cellulose, generally designated beta-cellulose, is decreased by conversion into the alpha-cellulose component which has the property of greater tensile strength, and the additional alpha-celluso lose formed by this conversion contributes to the total strength of the fibre.

This treatment of cellulose can be applied after the cellulose is prepared into commercial fibres, such as thread or cord, or woven into fabrics, and, because of the. fact that the exposure to ultraviolet is relatively brief, the process does not slow down or otherwise affect the production of commercial material.

My invention is also applicable, for instance, to the treatment of clothes in process of being laundered in commercial laundries, for the reason that the factors in the process can be arranged to conform to standard laundry practice with respect to the speed at which clothes are handled 0t inany of the steps or stages in the laundry operations.

r I claim:

1. The process of imparting the property of increased tensile strength to cellulose, which consists in subjecting cellulose to the action of artificially produced ultra-violet radiation and controlling the action thereof to prevent the formation of detectable oxycellulose in said cellulose.

2. The process of imparting the property of 105 increased tensile strength to cellulose, which consists in subjecting the cellulose to the action of artificially produced ultra-violet radiation of given volume and intensity for a period of time and no stopping said action prior to the formation of detectable oxycellulose.

3-. The herein described process which consists in strengthening cellulose fibre by exposing the cellulose to the action of ultra-violet radiation of given volume and intensity produced by a mercury vapor arc in quartz at a distance of substantially six inches from said are and controlling the time of exposure to avoid the formation of detectable oxycellulose in said cellulose.

4. The herein described process which consists in strengthening cellulose fibre by exposing the cellulose for a period of time not in excess of fifteen minutes to the action of ultra-violet radiation such as produced by a mercury vapor a second, and of such volume and intensity as I will not form detectable oxycellulose during said period of exposure.

AUGUST J. PACINI. 

